Apache IP-based Virtual Host Support

See also: Name-based Virtual Hosts Support

System requirements

As the term IP-based indicates, the server must have a different IP address for each IP-based virtual host. This can be achieved by the machine having several physical network connections, or by use of virtual interfaces which are supported by most modern operating systems (see system documentation for details).

How to set up Apache

There are two ways of configuring apache to support multiple hosts. Either by running a separate httpd daemon for each hostname, or by running a single daemon which supports all the virtual hosts.

Use multiple daemons when:

The different virtual hosts need very different httpd configurations, such as different values for: ServerType, User, Group, TypesConfig or ServerRoot.
The machine does not process a very high request rate.

Use a single daemon when:

Sharing of the httpd configuration between virtual hosts is acceptable.
The machine services a large number of requests, and so the performance loss in running separate daemons may be significant.

Setting up multiple daemons

Create a separate httpd installation for each virtual host. For each installation, use the Listen directive in the configuration file to select which IP address (or virtual host) that daemon services. e.g.

    Listen www.smallco.com:80

It is recommended that you use an IP address instead of a hostname (see DNS page).

Setting up a single daemon with virtual hosts

For this case, a single httpd will service requests for the main server and all the virtual hosts. The VirtualHost directive in the configuration file is used to set the values of ServerAdmin, ServerName, DocumentRoot, ErrorLog and TransferLog or CustomLog configuration directives to different values for each virtual host. e.g.

    <VirtualHost www.smallco.com>
    ServerAdmin webmaster@mail.smallco.com
    DocumentRoot /groups/smallco/www
    ServerName www.smallco.com
    ErrorLog /groups/smallco/logs/error_log
    TransferLog /groups/smallco/logs/access_log
    </VirtualHost>

    <VirtualHost www.baygroup.org>
    ServerAdmin webmaster@mail.baygroup.org
    DocumentRoot /groups/baygroup/www
    ServerName www.baygroup.org
    ErrorLog /groups/baygroup/logs/error_log
    TransferLog /groups/baygroup/logs/access_log
    </VirtualHost>

It is recommended that you use an IP address instead of a hostname (see DNS page).

Almost any configuration directive can be put in the VirtualHost directive, with the exception of ServerType, StartServers, MaxSpareServers, MinSpareServers, MaxRequestsPerChild, BindAddress, Listen, PidFile, TypesConfig, ServerRoot and NameVirtualHost.

User and Group maybe used inside a VirtualHost directive if the suEXEC wrapper is used.

SECURITY: When specifying where to write log files, be aware of some security risks which are present if anyone other than the user that starts Apache has write access to the directory where they are written. See the security tips document for details.